Spread

The spread is the gap between the rate at which you can buy an asset and the rate at which you can sell it back, quoted by whoever is providing liquidity for the swap.

Every exchange partner needs some margin to cover the cost of holding inventory, managing risk, and providing instant liquidity across many asset pairs. That margin shows up as the spread: a slightly less favorable rate baked into the quote itself, rather than a separate line-item fee. Spreads tend to be tight for high-volume pairs like BTC/USDT and wider for thinly traded or exotic pairs, where liquidity providers take on more risk holding the asset. This is a structural feature of the quote, not a timing effect — which is what separates it from slippage, where the rate moves between quote and execution because of market activity.

Spread matters when comparing swap costs, because it's often invisible unless you check the rate against an external price reference. A quote that looks "fee-free" can still embed a wide spread. When you're moving meaningful value, even a fraction of a percent in spread adds up, so it's worth glancing at the quoted rate relative to the broader market before confirming a swap — especially for less common pairs.

On Zest, the quoted rate you see already reflects the spread an exchange partner is offering for that pair, so there's no separate hidden markup to account for beyond what's shown at checkout. The rate you're quoted is the rate that determines your output amount, whether you choose a fixed-rate order (which locks that rate for a limited window) or a floating-rate order (which continues tracking the market, including any spread, until your deposit is processed) — see fixed vs. floating rate for how that choice plays out.

Spread and slippage are often confused because both reduce the final amount you receive relative to a naive expectation, but they come from different sources: spread is the liquidity provider's built-in margin, present in every quote regardless of timing; slippage is the additional drift caused by price movement between quote and settlement. Understanding the distinction helps you diagnose why a swap's output differs from what you expected — a wide spread on an obscure pair versus a fast-moving market during a volatile swap are two different problems with two different fixes: shopping the pair's liquidity, or choosing a fixed-rate order to remove the timing variable.